<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let persons = [
            {
                username: '张飞',
                sex: '男',
                salary: 50000
            },
            {
                username: '关羽',
                sex: '男',
                salary: 60000
            }
        ]
        var  newArr = JSON.parse(JSON.stringify(persons));
        console.log(persons);  
        for(var i=0;i<newArr.length;i++){
            newArr[i].salary +=2000; 
        }   
        console.log(newArr);
    </script>
</body>

</html>